Sorbitol dehydrogenase, also known as glucitol, polyol, or L-iditol dehydrogenase, catalyzes the oxidation of sorbitol to fructose with NAD as a cofactor. It has been detected in a wide variety of animals, plants and microorganisms. Impaired activity of SDH, resulting in accumulation of sorbitol within cells, has been implicated in the etology of cerebral edema and diabetic polyneuropathy. The structure information of sorbitol dehydrogenase could be used to design inhibitors and drugs.